<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .main {
            display: flex;

        }

        .left {
            height: 100vh;
            width: 50%;
            overflow-x: hidden;
            overflow-y: auto;
        }

        .right {
            height: 100vh;
            width: 50%;
            overflow-x: hidden;
            overflow-y: auto;
        }

        #red {
            height: 75vh;
            background-color: red;
        }

        #blue {
            height: 75vh;
            background-color: blue;
        }

        #yellow {
            height: 75vh;
            background-color: yellow;
        }

        #green {
            height: 75vh;
            background-color: green;
        }
    </style>
</head>

<body>
    <div class="main">
        <div class="left">
            <div id="red"></div>
            <div id="blue"></div>
            <div id="red"></div>
            <div id="blue"></div>
        </div>
        <div class="right">
            <div id="yellow"></div>
            <div id="green"></div>
            <div id="yellow"></div>
            <div id="green"></div>
            <div id="yellow"></div>
            <div id="green"></div>
        </div>
    </div>
</body>
<script>

</script>

</html>